The always @() block is sensitive to change of the values all the variables, that is read by always block or we can say which are at the right side inside the always block. In your example, there are no any variables used inside always block, so this always @() block will not work here. As per SV LRM, always_comb is sensitive to changes within the contents of a function, whereas always @* is ...
The (*) means "build the sensitivity list for me". For example, if you had a statement a = b + c; then you'd want a to change every time either b or c changes. In other words, a is "sensitive" to b & c. So to set this up: always @( b or c ) begin a = b + c; end But imagine you had a large always block that was sensitive to loads of signals. Writing the sensitivity list would take ages. In fact ...
verilog - What does always block @ (*) means? - Stack Overflow
I'm a bit confused about what is considered an input when you use the wildcard @* in an always block sensitivity list. For instance, in the following example, which signals are interpreted as inputs
The always @() syntax was added to the IEEE Verilog Std in 2001. All modern Verilog tools (simulators, synthesis, etc.) support this syntax. Here is a quote from the LRM (1800-2009): An incomplete event_expression list of an event control is a common source of bugs in register transfer level (RTL) simulations. The implicit event_expression, @, is a convenient shorthand that eliminates these ...